The invention has to do with a device for determining the position and/or torsion of rotating shafts.
A rotary angle sensor for determining the position of rotating shafts is known from the international patent publication No. WO 92/107,22. A bipolar-radially magnetized annular magnet is placed on the shaft, which is enclosed by a stator. Two oppositely-placed air gaps are built into the stator. A Hall element is placed in one of the air gaps.
If the annular magnet rotates in the stator, the Hall element records only one Hall voltage curve in dependence on the position angle, which curve runs similar to a sine wave. If the shaft turns by 360.degree., it is thus only possible to measure in the linear area of a quadrant, or only from 0.degree. to 90.degree.. The rounded and flattened parts of the Hall voltage curve are unsuited for measurement purposes. In fact, if the linear area in the first quadrant from 0.degree. to 90.degree. is followed by another in the third quadrant from 180 to 270.degree., then this, by reason of the intermediate rounded and offset parts, cannot be used for measurement of a position within a full turn.
A rotary angle sensor is known from the international patent publication No. WO 95 14 911 A1. It consists of a stationary and a rotating component. The stationary component has two crescent-shaped stator component elements, which are arrayed to be opposite while retaining a spacer recess. The rotating component is an annular magnetic element which is retained by a magnet mounting unit, which is connected to a shaft.
The disadvantage is that only one Hall element is placed in the spacer recess. This makes it possible to determine only one shaft setting between 0.degree. and 90.degree..
A measuring device for determining torsion of a rotating shaft is known from the German patent No. DE 42 31 646 A1. However, here two annular bodies are placed onto the shaft. The bodies are kept on the shaft by intermediate rings and equipped with teeth, between which there are gaps. By means of a plastic ring, an additional body with teeth is attached, so that an air gap results. An annular yoke is placed about the body, so that four coils are embedded in annular fashion. Projections form an additional air gap. A source of alternating current is applied to the coils, and thus an alternating magnetic field is induced. Torsion in the shaft causes a displacement of the two measuring units from each other. The resulting change of voltage in the pickup coils is therefore a measurable value.
A device to measure torsion and/or relative angular movement is described in the German patent No. DE 42 32 993 A1. In it, on one side of a first coil arrangement, a first and second annular element, shaped like pineapple or orange slices, are placed at different widths and at equal intervals. On one of the lateral surfaces of a second coil arrangement, third, fourth and fifth similarly-shaped annular segments are attached. This device measures two straight-running curves whose output signals are 0 in the crossing point, which corresponds to a torsion or angular motion.
Finally, an arrangement for determining torsion, torsion moment and/or rotary angle of at least two shafts that are connected with each other is known from the German patent No. DE 42 32 994 A1. In this patent, in the area where the two shafts are connected, there are two coil devices, which retain an air gap. The device operates according to the transformer principle. However, it only detects voltages that occur with a change in rotary angle and are dependent with that change in rotary angle.